High frequency high voltage insulation diagnostic method, apparatus, device, and medium

Abstract

The application relates to a high-frequency high-voltage insulation diagnosis method, device, equipment and medium, and relates to the technical field of fault diagnosis. The method comprises the following steps: acquiring first partial discharge quantity data of a to-be-tested equipment under a plurality of first voltages in a running voltage interval and a plurality of first frequencies in a running voltage frequency interval; determining a turning point frequency of the to-be-tested equipment based on the first partial discharge quantity data of the to-be-tested equipment under each first voltage and first frequency; and determining an insulation performance state of the to-be-tested equipment based on the turning point frequency and second partial discharge quantity data of a sample equipment, wherein the second partial discharge quantity data is obtained by measuring the sample equipment under different voltages and different frequencies by a measuring device. The method can obtain accurate diagnosis results.

Description

Technical Field

[0001] This invention relates to the field of fault diagnosis technology, and in particular to a high-frequency high-voltage insulation diagnosis method, apparatus, equipment, and medium. Background Technology

[0002] In the complex operating environment of power systems, overvoltages are often closely related to various sudden operating conditions. Besides normal operations (such as the opening and closing of switches) and grounding faults, lightning strikes, equipment switching moments, and system resonance can all trigger drastic electromagnetic energy conversion between inductive and capacitive components, thus initiating an oscillating transient process. This transient process is not isolated; the resulting overvoltages exhibit significant transient characteristics. Although their duration is short (typically ranging from microseconds to milliseconds), their amplitude can be several times or even tens of times that of normal operating voltage. More importantly, these overvoltages cover a very wide frequency range, extending from low frequencies of tens of Hz to high frequencies of tens of MHz. The impact and damage to electrical equipment insulation vary significantly depending on the frequency of the overvoltage. For example, high-frequency overvoltages are more likely to penetrate weak points in the insulation through capacitive coupling within the equipment, while low-frequency overvoltages, due to their relatively longer duration, can cause the insulating medium to endure high electric field stress for an extended period.

[0003] Under high frequency and high voltage, the insulating medium will undergo periodic polarization, which will cause the power loss to increase proportionally. At the same time, it will excite the internal residual charge, causing insulation degradation, and ultimately put the insulation performance of electrical equipment to a test.

[0004] Currently, the diagnosis of insulation performance such as dielectric loss has problems such as the test voltage being relatively low compared to the operating voltage and the frequency being fixed, which ultimately leads to inaccurate diagnostic results for insulation performance such as dielectric loss. Summary of the Invention

[0005] This invention provides a high-frequency high-voltage insulation diagnostic method, apparatus, equipment, and medium that can obtain accurate diagnostic results.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a high-frequency, high-voltage insulation diagnostic method, comprising:

[0008] Acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range;

[0009] Based on the first partial discharge data of the device under test at each first voltage and first frequency, the inflection frequency of the device under test is determined.

[0010] Based on the inflection point frequency and the second partial discharge quantity data of the sample device, the insulation performance status of the device under test is determined; wherein, the second partial discharge quantity data is obtained by measuring the sample device under different voltage and frequency conditions.

[0011] In one embodiment, the measuring device includes a high-frequency power supply, an excitation transformer, a low-voltage compensation reactor, a protective resistor, a capacitive voltage divider, a voltmeter, and a partial discharge measuring instrument.

[0012] The high-frequency power supply output is connected to one end of the input winding of the excitation transformer and one end of the low-voltage compensation reactor. The other end of the low-voltage compensation reactor is connected to the other end of the input winding of the excitation transformer, forming a parallel circuit between the low-voltage compensation reactor and the input side of the excitation transformer. One end of the output winding of the excitation transformer is connected in series with a protection resistor and then connected to one end of the device under test. The other end of the device under test is connected to one end of the high-voltage arm capacitor of the capacitor divider and the circuit grounding terminal. The other end of the high-voltage arm capacitor of the capacitor divider is connected to one end of the low-voltage arm capacitor. The other end of the low-voltage arm capacitor is grounded, and the partial discharge measuring instrument is connected in parallel across the two ends of the low-voltage arm capacitor to form a complete test circuit.

[0013] In one embodiment, determining the inflection point frequency of the device under test (DUT) based on first partial discharge data at various first voltages and first frequencies includes:

[0014] For each first voltage, curve fitting is performed on the first partial discharge quantity data at each first frequency corresponding to that first voltage to obtain a first relationship curve; wherein, the first relationship curve is the relationship curve between the first frequency and the partial discharge quantity of the device under test at each first voltage.

[0015] For each first relationship curve, calculate the rate of change of each inflection point in the first relationship curve to obtain the candidate inflection point rate of change;

[0016] The rate of change of each candidate inflection point was screened to obtain the rate of change of the first inflection point;

[0017] The frequency corresponding to the first inflection point rate of change is determined as the inflection point frequency of the device under test.

[0018] In one embodiment, the sample device is a device of the same model and voltage level as the device under test and that meets the preset performance standards.

[0019] In one embodiment, determining the insulation performance status of the device under test based on the inflection point frequency and the second partial discharge quantity data of the sample device includes:

[0020] Based on the inflection point frequency and the second partial discharge quantity data, partial discharge quantity data corresponding to different voltages at the inflection point frequency are selected from the second partial discharge quantity data and used as the third partial discharge quantity data.

[0021] The third partial discharge quantity data is fitted to obtain the second relationship curve corresponding to the sample device; wherein, the second relationship curve is the relationship curve between voltage and partial discharge quantity of the sample device at the inflection point frequency;

[0022] Based on the second relationship curve and the first partial discharge data, the insulation performance status of the device under test is determined.

[0023] In one embodiment, determining the insulation performance status of the device under test based on the second relationship curve and the first partial discharge quantity data includes:

[0024] The partial discharge data of the device under test at different voltages at the inflection point frequency are extracted from the first partial discharge data to obtain the measured data set of the device under test.

[0025] Based on the measured dataset and the second relationship curve, the first deviation corresponding to the device under test under each first voltage is obtained; wherein, the first deviation is the absolute difference between the partial discharge quantity of the device under test under the first voltage and the partial discharge quantity corresponding to the same first voltage in the second relationship curve;

[0026] Based on the first deviation and the preset deviation threshold, the insulation performance status of the device under test is determined.

[0027] In one embodiment, determining the insulation performance status of the device under test based on a first deviation and a preset deviation threshold includes:

[0028] If the first deviation is less than the preset deviation threshold, the insulation performance of the device under test is good.

[0029] Otherwise, the insulation performance of the device under test is considered dangerous.

[0030] Secondly, the present invention provides a high-frequency high-voltage insulation diagnostic device, comprising:

[0031] The acquisition module is used to acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range.

[0032] The inflection point determination module is used to determine the inflection point frequency of the device under test based on the first partial discharge data of the device under test at each first voltage and first frequency.

[0033] The insulation performance determination module is used to determine the insulation performance status of the device under test based on the inflection point frequency and the second partial discharge quantity data of the sample device; wherein, the second partial discharge quantity data is obtained by the measuring device measuring the sample device under different voltage and different frequency conditions.

[0034] Thirdly, the present invention provides a computing device, including a memory and a processor;

[0035] The memory stores one or more computer programs, the one or more computer programs including instructions; when the instructions are executed by the processor, the computing device performs the method as described in any one of the first aspects.

[0036] Fourthly, the present invention provides a computer-readable storage medium for storing a computer program for performing the method as described in any one of the first aspects.

[0037] Fifthly, the present invention provides a computer program product comprising one or more computer instructions, wherein when the computer instructions are executed by a computer, the computer performs the method as described in any one of the first aspects.

[0038] As can be seen from the above technical solution, the present invention has at least the following beneficial effects:

[0039] In this invention, by acquiring first partial discharge quantity data of the device under test (DUT) at multiple first voltages within the operating voltage range and multiple first frequencies within the operating voltage frequency range, a foundation is provided for subsequent accurate and targeted analysis. Furthermore, based on the first partial discharge quantity data of the DUT at each first voltage and first frequency, the inflection point frequency of the DUT is determined, fully exploring the key features in the partial discharge signal and laying a solid foundation for subsequent comparison with sample data. Subsequently, based on the inflection point frequency and the second partial discharge quantity data of the sample device, the insulation performance status of the DUT is determined, achieving an accurate diagnosis of the insulation status of the DUT. This solution achieves focused analysis of the discharge status of the device under test (DUT) under typical or critical operating conditions by selectively collecting first partial discharge data at multiple first voltages within a specific operating voltage range and multiple first frequencies within an operating voltage frequency range. This avoids data redundancy and interference, ensuring the validity and relevance of the original data. Furthermore, by introducing inflection point frequencies, the originally complex discharge data is transformed into characteristic parameters with clear physical meaning, simplifying the analysis process and capturing the core characteristics of insulation state changes. Finally, by introducing second partial discharge data from sample devices, the solution integrates the key characteristics of the DUT itself with the actual operating conditions of a large number of sample devices, effectively reducing the limitations of single-indicator judgment and ultimately improving diagnostic accuracy.

[0040] It should be understood that the descriptions of technical features, technical solutions, beneficial effects, or similar language in this invention do not imply that all features and advantages can be achieved in any single embodiment. Rather, it is understood that the description of a feature or beneficial effect means that a specific technical feature, technical solution, or beneficial effect is included in at least one embodiment. Therefore, the descriptions of technical features, technical solutions, or beneficial effects in this specification do not necessarily refer to the same embodiment. Furthermore, the technical features, technical solutions, and beneficial effects described in this embodiment can be combined in any suitable manner. Those skilled in the art will understand that embodiments can be implemented without one or more specific technical features, technical solutions, or beneficial effects of a particular embodiment. In other embodiments, additional technical features and beneficial effects may be identified in specific embodiments that do not embody all embodiments. Attached Figure Description

[0041] Figure 1 This is an application environment diagram of a high-frequency high-voltage insulation diagnostic method provided in an embodiment of the present invention;

[0042] Figure 2 This is a flowchart illustrating a high-frequency high-voltage insulation diagnostic method provided in an embodiment of the present invention;

[0043] Figure 3 This is a structural diagram of a measuring device provided in an embodiment of the present invention;

[0044] Figure 4 This is a schematic diagram of a process for determining the insulation performance status of a device under test, provided in an embodiment of the present invention.

[0045] Figure 5 This is a schematic diagram of the structure of a high-frequency power supply provided in an embodiment of the present invention;

[0046] Figure 6 This is a structural diagram of a low-voltage compensation inductor provided in an embodiment of the present invention;

[0047] Figure 7 This is a structural block diagram of a high-frequency high-voltage insulation diagnostic device provided in an embodiment of the present invention;

[0048] Figure 8 This is a schematic diagram of the internal structure of a computer device provided in the embodiments of the application. Detailed Implementation

[0049] The terms "first," "second," and "third," etc., used in this specification and description of the drawings are used to distinguish different objects, rather than to limit a specific order.

[0050] In embodiments of the present invention, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0051] To ensure clarity and conciseness in the description of the following embodiments, a brief introduction to the related technologies is given first:

[0052] During the operation of a power system, sudden changes in operating conditions, such as normal operation or grounding faults, can cause electromagnetic energy to be converted between inductive and capacitive components within the system, resulting in an oscillating transient process. This can generate overvoltages on equipment that exceed normal operating conditions, with frequencies ranging from tens of Hz to tens of MHz.

[0053] Under high frequency and high voltage, the insulating medium will undergo periodic polarization, which will cause the power loss to increase proportionally. At the same time, it will excite the internal residual charge, causing insulation degradation, and ultimately put the insulation performance of electrical equipment to a test.

[0054] Currently, insulation performance testing, such as dielectric loss, uses a relatively low voltage and a fixed frequency of approximately 10kV / 50Hz compared to the operating voltage. Furthermore, conventional high-frequency power supplies have low output power, and there is no test power supply capable of simultaneously adjusting the voltage to several hundred kV and the frequency to several thousand Hz. In addition, current insulation performance testing equipment suffers from the following problems:

[0055] (1) The high-frequency voltage of the power frequency transformer is severely attenuated, making it difficult to maintain high voltage output.

[0056] Traditional power frequency transformers exhibit significantly increased leakage reactance and distributed capacitance at frequencies in the kHz range, as does transformer leakage inductance. The impedance at high frequencies is Transformer input voltage With output voltage Attenuation ratio is ; Inter-winding distributed capacitance at specific high-frequency bands It forms a resonant circuit with the leakage inductance, and the resonant frequency is... Energy loss is aggravated, and under the combined effect of these two factors, the voltage amplitude of the transformer during high-frequency signal transmission is significantly attenuated; among them, Leakage inductance is the ability of an AC circuit to impede changes in current, also known as inductive reactance; f is the operating frequency. For load resistance; Distributed capacitance;

[0057] (2) Wideband reactive power compensation is difficult, and high voltage cannot be continuously output.

[0058] In the test setup system, capacitive loads (equivalent capacitive reactance) and inductive loads need to be dynamically matched; otherwise, the system reactive power will be too high, and the output voltage will be too low. The total reactive power of the test setup system... When satisfied Compensation is achieved in real time, compensating for inductance. ,in This refers to the equivalent capacitive reactance of the transformer. Traditional resonant technology operates within a frequency range of 20Hz to 300Hz. For a continuously adjustable frequency range of 0 to 1000Hz, the compensation inductance is too large, making it difficult to achieve wide-band reactive power compensation, resulting in the power supply being unable to output high-voltage. This is capacitive reactive power, generated by capacitors; It is inductive reactive power, generated by inductance;

[0059] (3) The high-frequency test device generates too much heat, which places high demands on the heat dissipation of the test device.

[0060] As the frequency increases, the eddy current losses and hysteresis losses of transformers and inductors increase exponentially. Joule heating rises significantly when current flows, and insufficient heat dissipation may burn out the components. Therefore, at high-frequency output voltages, the eddy current losses and hysteresis losses of transformers and inductors increase exponentially, leading to excessively high equipment temperatures.

[0061] Therefore, the existing problems in current insulation performance measurement tests, such as dielectric loss, lead to inaccurate results.

[0062] To make the technical solution of the present invention clearer and easier to understand, the application scenarios of the technical solution of the present invention will be described below with reference to the accompanying drawings. For example... Figure 1 As shown in the figure, this figure is an application environment diagram provided by an embodiment of the present invention.

[0063] In this application scenario, the control system 102 can communicate with the high-frequency power supply 104 via a communication network and has the function of remotely adjusting voltage and frequency, as well as multiple alarm protection functions such as over-harmonicity, low-voltage overcurrent, and power supply phase loss. The output voltage and frequency of the entire system, the voltage and current calibration coefficients, the upper and lower limits of the frequency, and the overcurrent setting value can be manually set. It also has a complete system status display function, which can display the current status of the power supply in real time. In addition to the conventional open and closed indication status, the status also includes the status of the fan, the temperature of the inlet and outlet air, the monitoring of the bridge arm voltage, and the pre-start indication status, so as to grasp the system's operating information in real time and facilitate the analysis of the cause when a fault occurs.

[0064] To make the technical solution of the present invention clearer and easier to understand, the method is applied to the above-mentioned application scenarios below. Figure 1Taking the control system 102 as an example, this invention provides a high-frequency high-voltage insulation diagnosis method. Figure 2 As shown in the figure, this is a flowchart illustrating a high-frequency high-voltage insulation diagnostic method provided by an embodiment of the present invention.

[0065] S201. Acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range.

[0066] The device under test (DUT) is an electrical device whose partial discharge performance needs to be tested (such as transformers, cables, capacitors, etc.). The insulation status is determined by measuring its partial discharge. The first voltage refers to each voltage within the operating voltage range, which is the voltage range the DUT may experience during actual operation (e.g., if the rated voltage is 110kV, the operating voltage range might be 80kV~120kV). The "first voltage" is a series of selected test voltage values ​​within this range (e.g., sequentially 80kV, 90kV…120kV) used to simulate the voltage stress of the DUT under different operating conditions. The first frequency refers to each frequency within the voltage frequency range. "Interval" can be the output high-frequency voltage range (e.g., determined by the high-frequency power supply and excitation transformer, such as 50Hz~500Hz), and "first frequency" can be the test frequency values ​​selected successively within this interval (e.g., 50Hz, 100Hz...500Hz) to simulate different high-frequency operating conditions; the first partial discharge quantity data is obtained by the measuring device under different voltage and frequency conditions. It can be the electrical signal data collected by the partial discharge measuring instrument in the measuring device, which can reflect the strength of the partial discharge of the device under test under the corresponding "first voltage, first frequency" (usually reflected by parameters such as discharge charge).

[0067] It should be noted that, as Figure 3 As shown, the measuring device includes a high-frequency power supply, an excitation transformer, a low-voltage compensation reactor (which can be used to adjust the frequency), a protective resistor, a capacitive voltage divider, a voltmeter, and a partial discharge measuring instrument. The output of the high-frequency power supply is connected to one end of the input winding of the excitation transformer and one end of the low-voltage compensation reactor. The other end of the low-voltage compensation reactor is connected to the other end of the input winding of the excitation transformer, forming a parallel circuit between the low-voltage compensation reactor and the input winding of the excitation transformer. One end of the output winding of the excitation transformer is connected in series with the protective resistor and then connected to one end of the device under test. The other end of the device under test is connected to one end of the high-voltage arm capacitor of the capacitive voltage divider and the circuit grounding terminal. The other end of the high-voltage arm capacitor of the capacitive voltage divider is connected to one end of the low-voltage arm capacitor, and the other end of the low-voltage arm capacitor is grounded. The partial discharge measuring instrument is connected in parallel across the two ends of the low-voltage arm capacitor to form a complete test circuit.

[0068] Optionally, a high-frequency power supply can refer to a power supply device with an operating frequency higher than a preset frequency, such as a preset frequency of 20kHz. The preset frequency can be adjusted according to the application field. The capacitor voltage divider needs to meet the requirements of voltage division and accurate measurement at the kHz level, such as a measurement range of 200kV, 500pF, pure AC, and 1.0 class.

[0069] The accuracy of a capacitor voltage divider can be as follows:

[0070] The partial pressure ratio K satisfies:

[0071] ;

[0072] Among them, the partial pressure ratio measurement error (This can be achieved by calibrating the capacitance value) , accomplish).

[0073] The high-frequency response correction is as follows:

[0074] Voltage divider bandwidth f BW satisfy:

[0075] To ensure that the phase offset is less than 1°.

[0076] in, This is the equivalent capacitance of the capacitor divider.

[0077] Optionally, the measuring device can output voltages from 0 to 200 kV and from 50 to 1 kHz with an accuracy of 0.1 Hz and a partial discharge quantity controlled within 50 PC. It can be used for insulation diagnostic tests of high-voltage electrical equipment operating at voltage levels of 220 kV and below.

[0078] For example, in combination Figure 3 First, the high-frequency power supply can be turned on to output initial electrical energy, and the excitation transformer, low-voltage compensation inductor, protection resistor, capacitive voltage divider, and partial discharge measuring instrument can be put into a ready-to-work state. Furthermore, the low-voltage compensation inductor can be adjusted, for example, by adjusting its inductance value (e.g., changing the number of turns or the position of the magnetic core) according to a preset voltage frequency range, in conjunction with the high-frequency power supply output frequency, so that the measuring device can output electrical energy at different frequencies. Simultaneously, the adjustment range of the high-frequency power supply output voltage can be set according to a preset operating voltage range to achieve sequential output of voltage values ​​within the operating voltage range. Furthermore, the measuring instrument can be configured, such as configuring the parameters of the partial discharge measuring instrument (e.g., sampling frequency, range), so that it can accurately acquire the partial discharge signal of the device under test.

[0079] Optionally, a high-frequency power supply can be controlled in conjunction with a low-voltage compensation reactor and an excitation transformer to output a "first voltage" sequentially according to the "operating voltage range" (e.g., starting from 80kV and gradually increasing to 120kV). After being stepped up by a low-impedance transformer, the high voltage is applied to both ends of the device under test. Alternatively, the low-voltage compensation reactor and the high-frequency power supply can be adjusted to output a "first frequency" sequentially according to the "voltage frequency range" (e.g., gradually increasing from 50Hz to 500Hz), so that the high voltage output by the excitation transformer has corresponding frequency characteristics, thus constructing test conditions of "different voltages + different frequencies". Furthermore, after each set of "first voltage, first frequency" has been applied and stabilized (it is necessary to wait for the voltage and frequency to stabilize to avoid transient interference), the partial discharge measuring instrument can collect the partial discharge signal of the device under test, record and store the corresponding "first partial discharge quantity data", which may include information such as discharge amplitude, number, and phase.

[0080] It should be noted that acquiring partial discharge data at multiple first voltages within the operating voltage range and multiple first frequencies within the operating voltage frequency range allows for targeted data acquisition, focusing on the partial discharge characteristics of the device under specific operating conditions. The first voltage and first frequency are selected based on the typical operating state of the device or fault diagnosis requirements; the intensity, mode, and other characteristics of partial discharge will differ under different voltage and frequency conditions. By acquiring partial discharge data at multiple first voltages within a specific operating voltage range and multiple first frequencies within the operating voltage frequency range, the discharge status of the device under key operating parameters can be directly captured, avoiding information omissions caused by general parameter selection. This ensures the correlation between the acquired data and the actual fault performance of the device, providing a valid original basis for subsequent accurate fault diagnosis.

[0081] Secondly, the first partial discharge quantity data contains information about the insulation defects inside the equipment, such as the magnitude and trend of the discharge quantity, which are closely related to the type and severity of the fault. Therefore, the first partial discharge quantity data provides a clear data object for the extraction and analysis of fault features. For example, based on data from multiple first voltages in a specific operating voltage range and multiple first frequencies in an operating voltage frequency range, it is possible to extract fault-related feature parameters more accurately (such as determining the inflection point frequency through spectrum analysis of the data). These feature parameters are key to distinguishing different fault types and assessing the degree of fault development. Reliable first partial discharge quantity data is a prerequisite for ensuring the accuracy of these feature parameters, thereby helping to improve the credibility of fault diagnosis results.

[0082] Furthermore, since the initial partial discharge data is acquired under specific and critical conditions, it directly reflects potential equipment malfunctions. Subsequent analysis based on this data, such as comparison with sample data and curve fitting, can reduce interference from irrelevant factors, making the diagnostic process more targeted and enabling rapid identification of the fault location and accurate assessment of its nature and severity. This not only avoids misdiagnosis and missed diagnosis but also provides clear direction for equipment repair and maintenance, improving fault handling efficiency and reducing the risk of equipment downtime and economic losses due to faults.

[0083] S202. Based on the first partial discharge data of the device under test at each first voltage and first frequency, determine the inflection point frequency of the device under test.

[0084] Among them, the inflection point frequency can characterize the frequency value of the "critical critical point" of the partial discharge characteristics of the device under test as the frequency changes. It is the core characteristic parameter for judging the insulation status of the device under test (for example, when the insulation of the device under test is good, the inflection point frequency may be stable in a certain range; when the insulation deteriorates, the inflection point frequency will shift, etc.).

[0085] One possible approach is to perform curve fitting on the partial discharge quantity data at each first frequency corresponding to each first voltage to obtain a first relationship curve; wherein, the first relationship curve is the relationship curve between the first frequency and the partial discharge quantity of the device under test at each first voltage; for each first relationship curve, the rate of change of each inflection point in the first relationship curve is calculated to obtain a candidate inflection point rate of change; the candidate inflection point rates of change are screened to obtain a first inflection point rate of change; and the frequency corresponding to the first inflection point rate of change is determined as the inflection point frequency of the device under test.

[0086] The first relationship curve is a mathematical curve obtained by curve fitting (such as polynomial fitting, exponential fitting, etc.) of multiple sets of data (frequency and discharge quantity) under the same "first voltage" with "first frequency" as the horizontal axis and "first partial discharge quantity data" as the vertical axis. It can reflect the change law of "frequency to discharge quantity" under the voltage. The candidate inflection point change rate can be the change rate corresponding to the "rate change point" of the partial discharge quantity with frequency on the "first relationship curve" (such as the change of slope when the curve changes from flat to steep). The first inflection point change rate is the most representative slope value selected from the candidate inflection point change rates. For example, the maximum value among the candidate inflection point change rates can be taken as the first inflection point change rate.

[0087] It should be noted that the inflection point is the key point where the trend of the curve changes, and the "rate of change" can be used to quantify the degree of this trend change, serving as a basis for screening "true inflection points".

[0088] For example, after each stable application of "first voltage + first frequency" (waiting for voltage and frequency to stabilize to avoid transient interference), the partial discharge measuring instrument can be triggered to collect data and record the "(voltage, frequency, discharge quantity)" triplet to form a basic dataset (assuming a total of n groups); furthermore, the basic data in the basic dataset can be grouped according to "first voltage" (e.g., group U1, group U2, ..., group U...). n The data can be divided into groups, each containing all (frequency, discharge quantity) data pairs under that voltage. Further, based on each group of data, with frequency as the independent variable and discharge quantity as the dependent variable, a fitting algorithm (such as least squares) can be used to perform curve fitting, generating a "first relationship curve" (i.e., each voltage corresponds to a first relationship curve, which is the curve showing the relationship between frequency and discharge quantity under that voltage). Further, the derivative of each first relationship curve can be calculated, for example, the fitted first relationship curve can be q=f(freq); where freq is the frequency, q is the discharge quantity, and f() represents the function that converts frequency to discharge quantity. By taking the derivative (e.g., using the first derivative to find the slope, using the second derivative to find inflection points), the rate of change of the curve at different frequency points, i.e., the slope, can be calculated. Then, based on the rate of change, candidate inflection points corresponding to each first relationship curve can be located. For example, based on the change in the derivative, the abrupt change point of the curve slope can be found, such as the point where the second derivative changes from positive to negative or vice versa, and these points can be marked as candidate inflection points. The frequency f corresponding to each candidate inflection point can be recorded. candidate Furthermore, the rate of change of candidate inflection points can be calculated. For example, at a candidate inflection point, the change in slope Δk before and after the abrupt change can be calculated. , (where k after The slope after the mutation, k before The slope before the mutation is used as the candidate inflection point change rate, forming a candidate inflection point frequency-candidate inflection point change rate list.

[0089] Furthermore, based on historical data of similar equipment and insulation theory models, an effective inflection point change rate threshold Δk can be set. threshold This is used to distinguish between true inflection points (caused by equipment characteristics) and noise interference points (caused by measurement errors). For example, the candidate inflection point change rate Δk can be compared with the effective inflection point change rate threshold Δk. threshold For comparison, if Δk ≥ Δk threshold If the candidate inflection point is found to be valid, its corresponding frequency is retained; otherwise, if it is found to be measurement noise or invalid, it is removed.

[0090] Furthermore, cross-voltage integration is carried out, that is, statistical analysis (such as calculating the mean and median) is performed on the "effective candidate inflection point frequencies" under different "first voltages" of the same device under test, and combined with the equipment insulation theory (such as insulation material characteristics, equipment structural design, etc.) to finally determine a unique or a set of "inflection point frequencies".

[0091] It is important to note that the inflection point frequency is a core node in the spectral characteristics of partial discharge signals in equipment, and its magnitude is closely related to the type and severity of insulation defects within the equipment. Different insulation faults (such as air gap discharge, surface discharge, and electrical tree aging) will cause the spectral distribution of partial discharge signals to exhibit different characteristics, and the inflection point frequency will also change regularly accordingly. Determining the inflection point frequency through the first partial discharge quantity data can transform the originally complex discharge signal into a characteristic parameter with clear physical meaning, accurately capturing the spectral changes caused by the fault, thus providing a reliable basis for distinguishing different fault types. For example, severe insulation aging may cause the inflection point frequency to shift towards lower frequencies, while partial tip discharge may cause the inflection point frequency to rise. This characteristic can be used to quickly narrow down the scope of fault investigation.

[0092] On the other hand, the determined inflection point frequency provides a unified and crucial reference benchmark for subsequent fault diagnosis. When assessing insulation performance based on the inflection point frequency and sample data, the inflection point frequency serves as a vital bridge connecting the device under test (DUT) and the sample device. Using this frequency as a benchmark to screen and compare relevant data ensures that the analysis focuses on the spectral characteristics most closely related to the fault, reducing errors and interference caused by inconsistent frequency benchmarks. This makes subsequent comparative analysis more targeted and scientific, thereby improving the consistency and reliability of fault diagnosis results and avoiding misjudgments due to inappropriate selection of characteristic parameters.

[0093] Furthermore, this process deepens the understanding of the fault's development trend. The change in inflection point frequency is often a dynamic process. By combining the first partial discharge data of the equipment at different times with the corresponding inflection point frequency, its changing trend can be tracked, thereby determining whether the fault is in a stable state, developing slowly, or rapidly deteriorating. This dynamic analysis capability provides crucial support for predicting the development direction of equipment faults and formulating reasonable maintenance strategies. It helps to take measures in advance to prevent fault escalation, reduce the risk of equipment downtime and accidents, and overall enhance the practical value of fault diagnosis.

[0094] In summary, determining the inflection point frequency based on the first partial discharge quantity data not only provides accurate features for distinguishing fault types, but also lays a unified benchmark for subsequent diagnostic procedures. Furthermore, it helps to grasp the development trend of faults and plays a crucial role in improving the accuracy, reliability, and practicality of fault diagnosis results.

[0095] S203. Based on the inflection point frequency and the second partial discharge data of the sample device, determine the insulation performance status of the device under test.

[0096] Among them, the sample equipment is the same model and voltage level as the equipment under test and meets the preset performance standards. It can be used to provide the benchmark data of "normal / good insulation status" as a "reference template" for the equipment under test. The benchmark data (i.e., the second partial discharge quantity data) formed under the same test conditions is used to compare and analyze with the measured data (i.e., the first partial discharge quantity data) of the equipment under test. The second partial discharge quantity data is obtained by measuring the sample equipment (i.e., qualified equipment) under different voltage and frequency conditions. That is, the partial discharge quantity data collected by the sample equipment using the same measuring device as the equipment under test under the same test conditions (such as the same voltage range and the same frequency range) is the "benchmark discharge quantity record" of the "qualified equipment" under standard operating conditions. The insulation performance status refers to the ability and state of the insulating material or insulating structure in the electrical equipment to maintain its insulation function under the action of electric field, temperature, mechanical stress, environmental factors (such as humidity and chemical corrosion). It can reflect whether the equipment can effectively prevent current leakage and withstand the rated voltage without breakdown, flashover or partial discharge faults.

[0097] It should be noted that the second partial discharge quantity data of the sample device is the baseline data formed by the sample device under the same test conditions as the device under test, and can be used for comparative analysis with the measured data of the device under test.

[0098] Optionally, the preset performance standards can be a set of performance indicators (such as the upper limit of partial discharge, the lower limit of insulation resistance, the range of dielectric loss factor, etc.) that are formulated based on industry standards, equipment factory requirements, insulation theory, etc., to determine whether the equipment is "qualified" and ensure that the sample equipment is a reference object with "good insulation condition". The benchmark data can be "second partial discharge data" generated by the sample equipment under "the same test process and the same environmental conditions as the equipment under test", which is the "ruler" for judging whether the equipment under test is "abnormal".

[0099] For example, based on the inflection point frequency, partial discharge data at different voltages corresponding to the inflection point frequency are selected from the second partial discharge data of the sample device and the first partial discharge data of the device under test; and these are compared (e.g., observing whether there is local high-frequency discharge but the overall spectrum does not shift significantly, to determine whether there is a special defect); furthermore, the results can be corrected by combining the operating years of the device under test, environmental factors, etc., and the insulation performance status of the device under test can be determined according to the corrected results, such as the insulation performance status of the device under test being "good" and suggesting a shortened testing cycle, or the result being "serious defect", etc.

[0100] It should be noted that this step achieves a deep integration of key features and sample experience, significantly improving the accuracy of fault diagnosis. The inflection point frequency is the core spectral feature of the partial discharge signal of the device under test (DUT), directly related to the essential attributes of internal insulation defects. The second partial discharge quantity data of the sample devices covers typical manifestations under different insulation states, representing accumulated experience verified through practice. Furthermore, combining the two captures both the individual characteristics of the DUT and leverages the regularity of the sample data, avoiding the one-sidedness of judgment based on a single feature. For example, when the inflection point frequency of the DUT indicates a possible aging defect, comparing it with the second partial discharge quantity data of different insulation states at the same inflection point frequency in the sample can accurately determine whether its aging degree constitutes a fault, effectively reducing misjudgments caused by individual differences or environmental interference.

[0101] Secondly, this step provides a quantitative basis for the detailed differentiation of fault types and the assessment of severity. Different fault types (such as insulation dampness, partial breakdown, and material degradation) exhibit specific combinations of characteristics in terms of inflection point frequency and partial discharge quantity. The second partial discharge quantity data of the sample equipment contains the correspondence of these characteristics. By matching the inflection point frequency of the device under test with the sample data, the specific type of fault can be identified by combining the numerical range of the second partial discharge quantity. At the same time, based on the partial discharge quantity thresholds corresponding to different insulation states (good, minor fault, and severe fault) in the sample data, the severity of the fault in the device under test can be quantitatively assessed, providing a scientific reference for determining the priority of fault handling and avoiding the crude judgment of "one-size-fits-all" fault identification.

[0102] Furthermore, it enhances the universality and reliability of fault diagnosis. The second partial discharge data of the sample equipment typically comes from the actual measurement results of a large number of similar equipment, covering the insulation state characteristics under different operating environments and service years, and has strong representativeness and universality. Combining the inflection point frequency of the device under test with such sample data is equivalent to leveraging the collective experience of similar equipment, reducing the impact of individual special circumstances of the device under test (such as manufacturing differences or occasional interference) on the diagnostic results. Even if the partial discharge signal of the device under test has certain fluctuations, by comparing it with the overall trend at the same inflection point frequency in the sample data, abnormal characteristics can still be accurately identified, ensuring the consistency and reliability of diagnostic results across different devices.

[0103] Furthermore, this step provides a clear direction for fault tracing and prevention. By determining the insulation performance status of the equipment under test and its corresponding inflection point frequency and partial discharge characteristics, the possible causes of the fault can be deduced in reverse (such as whether the inflection point frequency shift is caused by long-term overvoltage operation, or whether the partial discharge exceeds the standard due to material defects). Combined with the fault development history of similar equipment in the sample data, the evolution path of the fault can be predicted, providing a basis for formulating targeted preventive measures (such as adjusting the operating voltage and strengthening insulation maintenance), reducing the possibility of fault recurrence from the source, and improving the safety and stability of equipment operation.

[0104] In summary, the insulation performance status of the device under test is determined based on the inflection point frequency and the second partial discharge data of the sample device. By integrating individual characteristics and group experience, the accuracy, quantification, and universality of fault diagnosis are achieved, which plays a decisive role in improving the accuracy and reliability of fault diagnosis results and its value in guiding practice.

[0105] The aforementioned high-frequency, high-voltage insulation diagnostic method acquires first partial discharge data of the device under test (DUT) at multiple first voltages and multiple first frequencies within the operating voltage frequency range, providing a foundation for subsequent precise and targeted analysis. Furthermore, based on the first partial discharge data of the DUT at each first voltage and first frequency, the inflection point frequency of the DUT is determined, fully exploring the key features in the partial discharge signal and laying a solid foundation for subsequent comparison with sample data. Finally, based on the inflection point frequency and the second partial discharge data of the sample device, the insulation performance status of the DUT is determined, achieving accurate diagnosis of the insulation status of the DUT. This solution achieves focused analysis of the discharge status of the device under test (DUT) under typical or critical operating conditions by selectively collecting first partial discharge data at multiple first voltages within a specific operating voltage range and multiple first frequencies within an operating voltage frequency range. This avoids data redundancy and interference, ensuring the validity and relevance of the original data. Furthermore, by introducing inflection point frequencies, the originally complex discharge data is transformed into characteristic parameters with clear physical meaning, simplifying the analysis process and capturing the core characteristics of insulation state changes. Finally, by introducing second partial discharge data from sample devices, the solution integrates the key characteristics of the DUT itself with the actual operating conditions of a large number of sample devices, effectively reducing the limitations of single-indicator judgment and ultimately improving diagnostic accuracy.

[0106] Based on the above embodiments, the present invention provides a detailed explanation of S203. Specifically, the present invention involves a process for determining the insulation performance status of the device under test, such as... Figure 4 As shown, the specific steps include:

[0107] S401. Based on the inflection point frequency and the second partial discharge quantity data, select the partial discharge quantity data corresponding to different voltages at the inflection point frequency from the second partial discharge quantity data, and use it as the third partial discharge quantity data.

[0108] Among them, the third partial discharge quantity data is selected from the second partial discharge quantity data, and the partial discharge quantity data corresponding to the inflection point frequency under different voltage conditions are selected. That is, based on the second partial discharge quantity data, combined with the key feature of the inflection point frequency, the partial discharge quantity information with specific correlation is extracted for different voltage scenarios, which provides targeted data support for more accurate analysis of the insulation performance status of the device under test.

[0109] For example, the frequency information in the second partial discharge quantity data can be matched with the inflection point frequency to establish a preliminary association index. For each frequency value, the corresponding voltage and partial discharge quantity data can be marked, making it convenient to quickly find data entries related to the inflection point frequency. Furthermore, based on the association index, all data entries with frequencies equal to the inflection point frequency can be filtered out. Then, these entries can be classified and organized according to different voltages, and the partial discharge quantity data corresponding to each voltage can be extracted to form the third partial discharge quantity data.

[0110] Optionally, the selected third partial discharge data can be verified to check whether its matching with the inflection point frequency and corresponding voltage is accurate. If abnormal data is found, such as the partial discharge value deviating significantly from the reasonable range, the original data needs to be rechecked, and correction or re-screening should be carried out if necessary to ensure the reliability of the third partial discharge data.

[0111] It should be noted that the established inflection point frequency can be used as the core benchmark, while also focusing on different voltage parameters. This is because the inflection point frequency reflects the key change point in the partial discharge signal spectrum, and the partial discharge quantity at different voltages exhibits different characteristics. Combining these two factors allows for precise location of the required data. In other words, this step significantly improves the relevance and effectiveness of the data, providing a high-quality analytical foundation for subsequent fault diagnosis. The second partial discharge quantity data may contain a large amount of information at different frequencies and voltages, including data with low correlation to the fault of the device under test. The inflection point frequency, however, is the core frequency point reflecting the characteristics of insulation defects in the equipment. Using this as a benchmark to filter out partial discharge quantity data corresponding to different voltages can eliminate redundant information at irrelevant frequencies, focusing the analysis on data closely related to fault characteristics. This makes the third partial discharge quantity data more accurately point to the discharge characteristics of the equipment at the key frequency, reducing the impact of interference factors on subsequent analysis and ensuring data reliability from the source.

[0112] Secondly, it provides a precise data source for subsequent fitting of the second relationship curve, indirectly improving the accuracy of fault diagnosis. Thirdly, the partial discharge quantity data is the direct basis for fitting the second relationship curve of the sample equipment, and its quality directly determines the reliability of the curve. The selected third partial discharge quantity data only includes the discharge quantity corresponding to different voltages at the inflection point frequency, ensuring that the fitted second relationship curve accurately reflects the intrinsic correlation between voltage and partial discharge quantity at that key frequency. A reliable second relationship curve is an important reference standard for subsequent comparison with data from the device under test. The higher the accuracy of the curve, the more accurate the judgment of the insulation performance status of the device under test, thereby reducing the risk of misjudgment of faults due to curve distortion.

[0113] Furthermore, it helps to highlight fault characteristics, making fault diagnosis more targeted. The variation pattern of partial discharge at different voltages is closely related to the type and severity of equipment faults, and this pattern is often more pronounced at the inflection point frequency, a critical frequency. Filtering out third partial discharge data can centrally display the discharge characteristics corresponding to different voltages at this frequency, facilitating clear observation of the trend of discharge quantity changes with voltage. For example, if the equipment has an insulation aging fault, at the inflection point frequency, the growth rate of its partial discharge quantity with increasing voltage may differ significantly from that of normal equipment. Third partial discharge data can clearly present this difference, providing strong support for accurate fault identification.

[0114] Furthermore, this step improves the efficiency of fault diagnosis. By filtering out irrelevant data, the workload of subsequent data processing and analysis is reduced, making the diagnostic process simpler and more efficient. Simultaneously, focusing on the analysis of key data allows diagnostic personnel to quickly grasp core characteristics, shortening the fault diagnosis time and saving valuable time for timely fault handling, thus reducing the possibility of further damage to equipment due to continued operation of the fault. In summary, this step, through precise data filtering, improves data quality and relevance, provides a reliable foundation for subsequent analysis, strengthens the prominence of fault characteristics, and ultimately plays a crucial supporting role in improving the accuracy, efficiency, and reliability of fault diagnosis results.

[0115] S402. Fit the third partial discharge quantity data to obtain the second relationship curve corresponding to the sample device.

[0116] Among them, the second relationship curve is the relationship curve between voltage and partial discharge quantity of the sample equipment at the inflection point frequency. It can be used as voltage on the horizontal axis and partial discharge quantity on the vertical axis to intuitively present the change law of partial discharge quantity of the sample equipment with voltage change at the inflection point frequency. It is an important curve reflecting the insulation performance and voltage correlation characteristics of the sample equipment at this specific frequency.

[0117] Optionally, a suitable fitting method can be selected based on the distribution characteristics of the third partial discharge quantity data. If the data shows a clear linear relationship, a linear fitting method can be used, and the linear regression equation between voltage and partial discharge quantity can be calculated using the least squares method. If the data shows a nonlinear relationship, such as a quadratic function relationship or an exponential relationship, then an appropriate nonlinear fitting method needs to be selected. When selecting a fitting method, the fitting effect can be evaluated by calculating the goodness of fit of different fitting methods, and the method with a higher goodness of fit should be given priority.

[0118] For example, fitting operations can be performed using professional data processing software (such as Excel, Origin, MATLAB, etc.). For instance, the voltage value in the preprocessed third partial discharge data can be used as the independent variable and the partial discharge quantity as the dependent variable. The software can then select a predetermined fitting method and automatically calculate the parameters of the fitting curve (such as the slope and intercept of the linear equation, the coefficients of the nonlinear equation, etc.) and generate the corresponding second relationship curve.

[0119] Optionally, the obtained second relationship curve can be verified. For example, observe the degree of fit between the second relationship curve and the third partial discharge quantity data points. If most data points fall well near the curve, the fitting effect is good. Furthermore, some third partial discharge quantity data that were not included in the fitting (if they exist) can be selected, and their voltage values ​​can be substituted into the fitting curve equation to calculate the corresponding predicted partial discharge quantity value. This value can then be compared with the actual measured value. The predictive ability of the curve can be evaluated by calculating the error (such as absolute error and relative error). If the error is within an acceptable range, the fitting result is reliable. Further, the obtained second relationship curve can be stored in a suitable format (such as image format, data table format, etc.) and clearly labeled with information such as the curve name (second relationship curve), inflection point frequency value, fitting equation, and goodness of fit, so that it can be consulted and used later when analyzing the insulation performance status of the device under test.

[0120] It should be noted that this step transforms the scattered third partial discharge data into a curve model with clear patterns, intuitively presenting the intrinsic relationship between voltage and partial discharge at the inflection frequency of the sample device. Although the third partial discharge data has been filtered to focus on the discharge at different voltages at the inflection frequency, it is still a series of discrete values. The second relationship curve obtained through fitting clearly shows the trend of partial discharge with voltage change at this key frequency (such as linear growth, nonlinear change, etc.). This regularity makes the normal state characteristics or fault characteristics of the sample device more prominent. For example, parameters such as the slope and intercept of the curve can be quantitatively reflected to reflect the sensitivity of the discharge to voltage, providing an intuitive reference scale for judging whether there is an anomaly in the device under test.

[0121] Secondly, it provides a standardized reference benchmark for comparing the device under test (DUT) with sample devices, significantly improving the accuracy of fault diagnosis. The second relationship curve is fitted based on the third partial discharge quantity data of a large number of sample devices, representing the typical voltage-partial discharge quantity relationship of similar devices at the inflection point frequency. When the measured data of the DUT is compared with this curve, the standardization characteristics of the curve allow the differences between the two to be accurately captured. Whether it is the degree to which the partial discharge quantity of the DUT deviates from the curve at a certain voltage, or the overall trend of change does not match the curve, it can clearly reflect the possible faults of the device. This comparison method based on standardized curves avoids the judgment bias caused by the discreteness of sample data, making the fault diagnosis results more objective and reliable.

[0122] Furthermore, it helps in the in-depth analysis of the nature and severity of the fault. The shape of the second relationship curve is closely related to the type and severity of the equipment fault. For example, if the curve shows a steep upward trend, it may correspond to a serious insulation defect in the sample equipment, with the discharge increasing sharply when the voltage rises; while a flat curve may represent good insulation condition of the equipment. By comparing the measured data of the equipment under test with the second relationship curve and observing the direction and magnitude of the deviation, the nature of the fault (such as whether it is insulation aging, air gap discharge, etc.) and its severity (such as minor defects, serious faults, etc.) can be inferred. This in-depth analysis provides an important basis for formulating targeted maintenance strategies and avoids the waste of resources caused by blind maintenance.

[0123] Furthermore, this step enhances the predictability of fault diagnosis. The second relationship curve not only reflects the current state of the sample equipment, but its underlying patterns can also provide a reference for predicting the development trend of equipment faults. By analyzing the deviation between the measured data and the curve of the equipment under test and the voltage variation, the development trend of the fault under different voltage conditions can be inferred, and potential problems of the equipment can be predicted in advance, providing support for preventive maintenance of the equipment and reducing the risk of sudden faults.

[0124] In summary, fitting the third partial discharge quantity data to obtain the second relationship curve, by regularizing discrete data, establishing standardized reference benchmarks, deeply analyzing fault characteristics, and enhancing predictability, provides a strong guarantee for the accuracy, scientificity, and practicality of fault diagnosis results, and is an indispensable key link in the fault diagnosis process.

[0125] S403. Based on the second relationship curve and the first partial discharge data, determine the insulation performance status of the device under test.

[0126] One possible approach is to extract partial discharge data of the device under test (DUT) at different voltages at the inflection point frequency from the first partial discharge data to obtain a measured dataset of the DUT; based on the measured dataset and a second relationship curve, obtain a first deviation corresponding to the DUT at each first voltage; wherein, the first deviation is the absolute difference between the partial discharge of the DUT at the first voltage and the partial discharge corresponding to the same first voltage in the second relationship curve; and based on the first deviation and a preset deviation threshold, determine the insulation performance status of the DUT.

[0127] Among them, the measured dataset refers to the set of partial discharge data of the device under test (DUT) at different voltages at the inflection point frequency, extracted from the first partial discharge data. It can directly reflect the actual partial discharge situation of the DUT under specific inflection point frequency and different voltage conditions. The first deviation is the absolute difference between the partial discharge of the DUT at a certain first voltage and the partial discharge corresponding to the same first voltage in the second relationship curve. It can intuitively reflect the degree of difference between the partial discharge of the DUT and the sample device at the same voltage and inflection point frequency, and is a key indicator for judging the insulation performance status.

[0128] For example, based on the determined inflection point frequency, all records corresponding to the inflection point frequency can be filtered from the first partial discharge quantity data; further, for the filtered records, the voltage value and the corresponding partial discharge quantity can be extracted, and these data can be sorted in order of voltage value to form an ordered measured dataset; further, for each voltage value in the measured dataset, the corresponding point can be found on the second relationship curve, and the theoretical value of the partial discharge quantity at that point can be read; then, the absolute difference between the actual partial discharge quantity of the device under test and the theoretical value of the partial discharge quantity at each voltage can be calculated, that is, the first deviation corresponding to each first voltage can be obtained.

[0129] Optionally, to make the comparison results more intuitive, the points of the measured dataset and the second relationship curve can be plotted on the same coordinate system, and the first deviation corresponding to each point can be marked. Finally, it can be determined whether the first deviation is within a reasonable range and the insulation performance status of the device under test can be determined.

[0130] Optionally, if the first deviation is less than a preset deviation threshold, the insulation performance of the device under test is considered good; otherwise, the insulation performance of the device under test is considered dangerous.

[0131] Among them, the preset deviation threshold can be a deviation value set in advance based on historical data of a large number of sample devices, evaluation criteria for insulation performance status, and actual engineering experience. It can be the boundary for measuring whether the first deviation is within a reasonable range. Different preset deviation thresholds correspond to different insulation performance status evaluation results.

[0132] For example, the specific value of the preset deviation threshold can be determined first, such as a preset deviation threshold of 10%. When the first deviation is less than the preset deviation threshold, the insulation performance of the device under test is good. This threshold can be set according to factors such as the type of equipment, service life, and industry standards, and can be divided into multiple levels, such as normal threshold, warning threshold, and fault threshold. For example, each calculated first deviation can be compared with the preset deviation threshold: if all first deviations are less than the normal threshold, it indicates that the insulation performance of the device under test is good; if some or all of the first deviations are between the normal threshold and the warning threshold, it indicates that the insulation performance of the equipment has deteriorated to a certain extent and needs to be monitored more closely; if any first deviation exceeds the warning threshold or even reaches the fault threshold, it means that there may be serious problems with the insulation performance of the equipment, and it needs to be repaired or replaced in time.

[0133] Optionally, the judgment process can also take into account factors such as the equipment's operating history and environmental conditions to ensure the accuracy of the evaluation results.

[0134] It should be noted that this step achieves a direct comparison between the sample patterns and the actual data of the device under test, accurately capturing the differences between the two and providing a clear basis for fault diagnosis. The second relationship curve is a summary of the relationship between voltage and partial discharge at the inflection point frequency of the sample device, representing the typical state of similar devices; while the first partial discharge data is the actual discharge record of the device under test under specific conditions. By comparison, it is possible to clearly discover the deviation of the partial discharge of the device under test from the sample patterns at the same voltage and inflection point frequency—whether the discharge at a single voltage point exceeds the curve range or the overall trend does not match the curve, it may indicate that the device under test has insulation defects. This direct difference comparison avoids the limitations of relying on subjective judgment based on experience, leaving no room for fault characteristics to hide, and laying the foundation for accurate fault identification.

[0135] Secondly, by quantifying differences (such as calculating the first deviation at each point), the severity of the fault can be accurately assessed, improving the objectivity of the diagnostic results. During the comparison process, by extracting the measured data set of the device under test and calculating the first deviation (absolute difference) from the second relationship curve at the same voltage, the abstract "difference" can be transformed into a concrete numerical value. Combined with a preset deviation threshold, it can be determined whether the insulation status of the device under test is "good," "slightly deteriorated," or "severely faulty." For example, if the first deviation at a certain voltage far exceeds the warning threshold, it indicates abnormally severe partial discharge at that voltage, potentially posing a serious risk of insulation breakdown; while a deviation within the normal range indicates stable equipment condition. This quantitative assessment method makes the fault diagnosis results more convincing and provides an operational standard for subsequent maintenance priority ranking. Furthermore, this step can be combined with the actual operating conditions of the device under test, enhancing the pertinence and reliability of the fault diagnosis. The first partial discharge data comes from actual measurements of the device under test (DUT) at multiple first voltages within the operating voltage range and multiple first frequencies within the operating voltage frequency range, reflecting its discharge characteristics under actual operating conditions. While the second relationship curve is based on samples, the consistency of the inflection point frequency ensures the correlation of the comparison. Through comparison, interference from differences in non-critical parameters between the samples and the DUT can be eliminated, focusing on the insulation performance at core frequencies and voltages. For example, if the DUT operates near the first voltage for a long period, comparing the discharge deviation at that voltage point can directly reflect its failure risk under common operating conditions, avoiding diagnostic bias caused by deviations from actual operating conditions, and making the results more closely match the actual usage requirements of the equipment.

[0136] Furthermore, this step verifies the effectiveness of the preceding analysis, forming a diagnostic closed loop and further ensuring the accuracy of the results. The rationality of the preceding steps, such as fitting the second relationship curve and determining the inflection point frequency, ultimately needs to be verified by comparing it with the first partial discharge quantity data. If the comparison results show that the differences conform to the expected pattern, it indicates that the parameter selection and analysis logic of the preceding steps are reliable; if abnormal deviations occur, the preceding steps can be traced back (e.g., whether the inflection point frequency is accurate, whether the selection of the third partial discharge quantity data is reasonable), and the diagnostic process can be corrected in a timely manner. This closed-loop verification mechanism reduces the impact of errors in a single step on the final result, improving the overall rigor of fault diagnosis.

[0137] In summary, based on the second relationship curve and the first partial discharge data, by accurately capturing differences, quantitatively assessing faults, combining actual operating conditions, and forming a closed-loop verification, the accuracy, objectivity, and reliability of fault diagnosis results are ultimately guaranteed. This is a key step in achieving accurate judgment of the insulation performance status of equipment.

[0138] In this embodiment of the invention, by introducing a second relationship curve, the intrinsic correlation between the voltage and partial discharge of the sample device at the inflection point frequency is clearly presented, and a standardized reference basis is provided for data comparison with the device under test, thus laying the foundation for accurate insulation performance judgment.

[0139] Based on the above embodiments, the present invention provides a detailed explanation of the measuring device in the above embodiments, such as... Figure 5 As shown, it specifically includes: a high-frequency power supply comprising a high-frequency signal generator, a signal modulation circuit, a wideband signal power amplification circuit, and a dynamic impedance matching network.

[0140] The high-frequency signal generator can employ DDS (Direct Digital Synthesizer) technology to generate a continuously adjustable (0.01Hz) sine wave signal. The high-frequency signal generator is connected in parallel with the signal modulation circuit, and the sine wave output from the high-frequency signal generator enters the signal modulation circuit. The signal modulation circuit can employ High-Frequency Pulse Width Modulation (PWM) technology, simultaneously using Digital Signal Processing (DSP). The processor, with a carrier frequency ≥100kHz, generates a high-precision sine wave signal and adjusts the switching frequency through closed-loop control to achieve continuous frequency adjustment (0.01Hz steps), producing a sine wave with a frequency 5~10 times that of traditional resonant circuits, and a sine wave harmonic distortion of <1%, achieving kHz-level frequency amplification. The wideband signal power amplifier unit can adopt a multi-stage modular amplification design: the wideband signal power amplifier unit consists of a three-stage amplification structure (pre-drive stage + intermediate amplification stage + output stage), with each stage having independently adjustable gain, supporting wideband (DC~10kHz) signal amplification, cascading to expand bandwidth and power capacity, overcoming the frequency limitation problem of traditional LC resonant circuits, and achieving a frequency output of 50~1000Hz. The dynamic impedance matching network can adopt dynamic impedance matching technology to monitor load impedance changes in real time, and adaptively adjust the output impedance to ensure efficient power transmission at different frequencies (50Hz~1kHz), reducing reflection loss. The matching circuit can be designed based on the Smith chart, and the LC parameters can be adjusted in real time to ensure the load impedance (±10%).

[0141] First, such as Figure 6As shown, the low-voltage compensation inductor can be composed of an input terminal, eight 145uH inductors, and an output cooling system. Specifically, the input terminal is connected to the high-frequency power supply output terminal, and the output terminal is connected to the low-voltage winding of the low-impedance transformer. The eight 145uH inductors are led out from both ends and connected in series and parallel through copper busbars to achieve outputs with different inductance values. This can be used to compensate for the lossless operation of the test device and solve the problem of excessive system current and insufficient voltage rise.

[0142] Furthermore, in order to address the issue of inductor leakage reactance and reactance heat generation under high-frequency conditions exceeding 50Hz... To address the major issues, a fan was installed inside the inductor box for heat dissipation. The power devices employed a liquid cooling system, combined with low thermal resistance packaging materials, to ensure stable operation under high frequency and high current conditions. Additionally, the heat sink was directly welded to the copper busbar to reduce contact thermal resistance.

[0143] The total inductance of the series and parallel inductors can be expressed as follows:

[0144] Total inductance in series It can be represented as:

[0145] ;

[0146] Where n1 is the number of inductors connected in series; The inductance of a single inductor;

[0147] For example, eight 145μH inductors connected in series, i.e. .

[0148] Total inductance in parallel It can be represented as:

[0149] ;

[0150] Where n2 is the number of inductors connected in parallel;

[0151] For example, three 145μH inductors connected in parallel, i.e. .

[0152] Hybrid - Four series and two parallel total inductance It can be represented as:

[0153] ;

[0154] The heat generated by an inductor can be represented as follows:

[0155] Single inductor Joule heating It can be represented as:

[0156] Where I is the current flowing through the inductor; R is the equivalent series resistance of the inductor; t is the time it takes for the current to flow; optionally, ( The quality factor can be taken as 50~100; f is the operating frequency.

[0157] The overall heat dissipation requirements and design principles can be summarized as follows:

[0158] ;

[0159] in, This represents the total power loss of all inductors; This represents the total number of inductors;

[0160] Since the cooling power needs to be dissipated through the fan, the following must be met:

[0161] ;

[0162] in, This is the minimum power that the cooling fan needs to provide in order to maintain stable system temperature;

[0163] Secondly, the low-impedance transformer can adopt an iron core structure, which is a single-column three-winding structure, including two low-voltage windings and one high-voltage winding, forming an ultra-low impedance special transformer to reduce the attenuation of high-frequency voltage; among them, the two low-voltage windings can both be four-tap, and can be selected individually to adjust the turns ratio; one end of the high-voltage winding is grounded, and the high-voltage output end is connected to a current-limiting resistor to protect the winding from the overcurrent impact generated when the test circuit is short-circuited.

[0164] It should be noted that the principle used in low-impedance transformers is as follows:

[0165] Leakage inductance calculation: ;

[0166] in, Leakage inductance is the inductance generated by the incomplete coupling of magnetic fields between the primary and secondary coils of a transformer. Let be the permeability in vacuum, a physical constant; N be the number of turns in the transformer coil; k be the coupling coefficient (which can be designed to be 0.99); and A be the cross-sectional area. The length of the magnetic circuit is [length missing]. To suppress high-frequency attenuation, the leakage inductance can be controlled by reducing the number of turns N and increasing the core cross-sectional area A. .

[0167] Secondly, the current-limiting resistor is connected to the high-voltage output terminal of the low-impedance transformer and to the high-voltage terminal of the capacitor divider. When a short circuit occurs at the high-voltage terminal of the transformer and its connection, the protection resistor limits the overcurrent surge and suppresses high-frequency oscillations, protecting the transformer windings from transient overcurrent surges. The protection resistor can be made of high-voltage resistant material, capable of withstanding voltages up to 200kV, ensuring stable operation under high-voltage conditions. The design heat dissipation power is ≥10kW, ensuring stable operation for a long time under high-current conditions. High-resistance material is used (to ensure effective current limitation under high voltage).

[0168] It should be noted that when designing the current-limiting resistor:

[0169] Limit short-circuit current:

[0170] ;

[0171] in, This is the maximum current flowing through the current-limiting resistor in the event of a short-circuit fault in the circuit. This represents the highest voltage value that may occur under normal or abnormal circuit conditions. This is the resistance value used to limit short-circuit current.

[0172] Design parameters include resistance and heat dissipation capacity, and the values ​​can be as follows:

[0173] Resistance: 50MΩ (withstand voltage 200kV, segmented structure to avoid partial discharge);

[0174] Heat dissipation capacity:

[0175] ;

[0176] in, This refers to the power loss generated by the current-limiting resistor during operation (especially under short-circuit conditions), which is also the heat that the resistor needs to dissipate through its heat dissipation capacity.

[0177] It should be noted that a ceramic substrate with an aluminum heat sink can be used to enhance heat dissipation.

[0178] The above text combined Figures 1 to 6 The high-frequency high-voltage insulation diagnosis method provided in the embodiments of the present invention has been described in detail. The apparatus and equipment provided in the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0179] like Figure 7 As shown in the figure, this is a structural block diagram of a high-frequency high-voltage insulation diagnostic device provided in an embodiment of the present invention. The high-frequency high-voltage insulation diagnostic device 500 includes: an acquisition module 501, an inflection point determination module 502, and an insulation performance determination module 503, wherein:

[0180] The acquisition module 501 is used to acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range.

[0181] The inflection point determination module 502 is used to determine the inflection point frequency of the device under test based on the first partial discharge data of the device under test at each first voltage and first frequency.

[0182] The insulation performance determination module 503 is used to determine the insulation performance status of the device under test based on the inflection point frequency and the second partial discharge quantity data of the sample device; wherein, the second partial discharge quantity data is obtained by the measuring device measuring the sample device under different voltage and different frequency conditions.

[0183] In one embodiment, the measuring device includes a high-frequency power supply, an excitation transformer, a low-voltage compensation reactor, a protective resistor, a capacitive voltage divider, a voltmeter, and a partial discharge measuring instrument. The output terminal of the high-frequency power supply is connected to one end of the input winding of the excitation transformer and one end of the low-voltage compensation reactor. The other end of the low-voltage compensation reactor is connected to the other end of the input winding of the excitation transformer, forming a parallel circuit between the low-voltage compensation reactor and the input winding of the excitation transformer. One end of the output winding of the excitation transformer is connected in series with the protective resistor and then connected to one end of the device under test. The other end of the device under test is connected to one end of the high-voltage arm capacitor of the capacitive voltage divider and the circuit ground terminal. The other end of the high-voltage arm capacitor of the capacitive voltage divider is connected to one end of the low-voltage arm capacitor, the other end of the low-voltage arm capacitor is grounded, and the partial discharge measuring instrument is connected in parallel across the two ends of the low-voltage arm capacitor to form a complete test circuit.

[0184] In one embodiment, the inflection point determination module 502 is specifically used for:

[0185] For each first voltage, curve fitting is performed on the first partial discharge quantity data at each first frequency corresponding to that first voltage to obtain a first relationship curve; wherein, the first relationship curve is the relationship curve between the first frequency and the partial discharge quantity of the device under test at each first voltage; for each first relationship curve, the rate of change of each inflection point in the first relationship curve is calculated to obtain the candidate inflection point rate of change; the candidate inflection point rate of change is screened to obtain the first inflection point rate of change; the frequency corresponding to the first inflection point rate of change is determined as the inflection point frequency of the device under test.

[0186] In one embodiment, the sample device is a device of the same model and voltage level as the device under test and that meets the preset performance standards.

[0187] In one embodiment, the insulation performance determination module 503 is specifically used for:

[0188] Based on the inflection point frequency and the second partial discharge quantity data, partial discharge quantity data corresponding to different voltages at the inflection point frequency are selected from the second partial discharge quantity data and used as the third partial discharge quantity data. The third partial discharge quantity data is fitted to obtain the second relationship curve corresponding to the sample device. The second relationship curve is the relationship curve between the voltage and the partial discharge quantity of the sample device at the inflection point frequency. Based on the second relationship curve and the first partial discharge quantity data, the insulation performance status of the device under test is determined.

[0189] In one embodiment, the insulation performance determination module 503 is specifically used for:

[0190] The partial discharge data of the device under test (DUT) at different voltages at the inflection point frequency are extracted from the first partial discharge data to obtain the measured dataset of the DUT. Based on the measured dataset and the second relationship curve, the first deviation of the DUT at each first voltage is obtained. The first deviation is the absolute difference between the partial discharge of the DUT at the first voltage and the partial discharge corresponding to the same first voltage in the second relationship curve. Based on the first deviation and the preset deviation threshold, the insulation performance status of the DUT is determined.

[0191] In one embodiment, the insulation performance determination module 503 is specifically used for:

[0192] If the first deviation is less than the preset deviation threshold, the insulation performance of the device under test is good; otherwise, the insulation performance of the device under test is dangerous.

[0193] The high-frequency high-voltage insulation diagnostic device 500 according to an embodiment of the present invention can correspond to performing the method described in the embodiment of the present invention, and the other operations and / or functions of each module / unit of the high-frequency high-voltage insulation diagnostic device 500 are respectively for implementing Figures 2 to 4 For the sake of brevity, the corresponding processes of each method in the illustrated embodiments will not be described in detail here.

[0194] This invention also provides a computing device. This computing device can be a local computing device or an application server.

[0195] like Figure 8 As shown in the figure, this is a schematic diagram of a computing device provided in an embodiment of the present invention. The computing device 700 includes a bus 701, a processor 702, a communication interface 703, and a memory 704. The processor 702, the memory 704, and the communication interface 703 communicate with each other via the bus 701.

[0196] The 701 bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 8 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0197] The processor 702 can be any one or more of the following processors: central processing unit (CPU), graphics processing unit (GPU), microprocessor (MP), or digital signal processor (DSP).

[0198] The communication interface 703 is used for external communication. For example, the communication interface 703 can be used to communicate with the control system 102. The communication interface 703 is used to send the insulation performance status of the device under test to the control system 102 so that the control system 102 can display the insulation performance status of the device under test.

[0199] Memory 704 may include volatile memory, such as random access memory (RAM). Memory 704 may also include non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid state drive (SSD).

[0200] The memory 704 stores executable code, and the processor 702 executes the executable code to perform the aforementioned high-frequency high-voltage insulation diagnosis method.

[0201] Specifically, in achieving Figure 7 In the case of the illustrated embodiment, and Figure 7 When the modules or units of the high-frequency high-voltage insulation diagnostic device described in the embodiments are implemented by software, the following steps are performed: Figure 7 The software or program code required for the functions of each module / unit can be partially or entirely stored in the memory 704. The processor 702 executes the program code corresponding to each unit stored in the memory 704 to perform the aforementioned high-frequency high-voltage insulation diagnosis method.

[0202] This invention also provides a computer-readable storage medium. The computer-readable storage medium can be any available medium that a computing device can store, or a data storage device such as a data center containing one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive). The computer-readable storage medium includes instructions that instruct the computing device to perform the aforementioned high-frequency, high-voltage insulation diagnostic method.

[0203] This invention also provides a computer program product comprising one or more computer instructions. When the computer instructions are loaded and executed on a computing device, all or part of the processes or functions described in this invention are generated.

[0204] The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, or data center to another website, computer, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means.

[0205] When the computer program product is executed by a computer, the computer performs any of the aforementioned high-frequency high-voltage insulation diagnostic methods. The computer program product can be a software installation package; when any of the aforementioned high-frequency high-voltage insulation diagnostic methods needs to be used, the computer program product can be downloaded and executed on the computer.

[0206] The descriptions of the processes or structures corresponding to the above figures each have their own emphasis. For parts of a process or structure that are not described in detail, please refer to the relevant descriptions of other processes or structures.

[0207] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-frequency, high-voltage insulation diagnostic method, characterized in that, The method includes: Acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range; Based on the first partial discharge data of the device under test at each first voltage and first frequency, the inflection frequency of the device under test is determined; wherein, the inflection frequency characterizes the frequency value of the critical point at which the partial discharge characteristics of the device under test change with frequency. Based on the inflection point frequency and the second partial discharge data of the sample device, the insulation performance status of the device under test is determined; wherein, the second partial discharge data is obtained by measuring the sample device under different voltage and frequency conditions. Based on the inflection point frequency and the second partial discharge data of the sample device, the insulation performance status of the device under test is determined, including: Based on the inflection point frequency and the second partial discharge quantity data, partial discharge quantity data corresponding to different voltages at the inflection point frequency are selected from the second partial discharge quantity data and used as the third partial discharge quantity data. The third partial discharge quantity data is fitted to obtain the second relationship curve corresponding to the sample device; wherein, the second relationship curve is the relationship curve between voltage and partial discharge quantity of the sample device at the inflection point frequency; Based on the second relationship curve and the first partial discharge data, the insulation performance status of the device under test is determined; Based on the second relationship curve and the first partial discharge quantity data, the insulation performance status of the device under test is determined, including: Extract the partial discharge data of the device under test corresponding to different voltages at the inflection point frequency from the first partial discharge data to obtain the measured data set of the device under test; Based on the measured dataset and the second relationship curve, the first deviation corresponding to the device under test under each first voltage is obtained; wherein, the first deviation is the absolute difference between the partial discharge amount of the device under test under the first voltage and the partial discharge amount corresponding to the same first voltage in the second relationship curve; Based on the first deviation and the preset deviation threshold, the insulation performance status of the device under test is determined.

2. The method according to claim 1, characterized in that, The measuring device includes a high-frequency power supply, an excitation transformer, a low-voltage compensation reactor, a protective resistor, a capacitive voltage divider, a voltmeter, and a partial discharge measuring instrument. The output of the high-frequency power supply is connected to one end of the input winding of the excitation transformer and one end of the low-voltage compensation reactor. The other end of the low-voltage compensation reactor is connected to the other end of the input winding of the excitation transformer, forming a parallel circuit between the low-voltage compensation reactor and the input winding of the excitation transformer. One end of the output winding of the excitation transformer is connected in series with the protective resistor and then connected to one end of the device under test. The other end of the device under test is connected to one end of the high-voltage arm capacitor of the capacitive voltage divider and the circuit grounding terminal. The other end of the high-voltage arm capacitor of the capacitive voltage divider is connected to one end of the low-voltage arm capacitor, the other end of the low-voltage arm capacitor is grounded, and the partial discharge measuring instrument is connected in parallel across the two ends of the low-voltage arm capacitor to form a complete test circuit.

3. The method according to claim 1, characterized in that, The step of determining the inflection point frequency of the device under test based on the first partial discharge quantity data of the device under test at each first voltage and first frequency includes: For each first voltage, curve fitting is performed on the first partial discharge quantity data at each first frequency corresponding to that first voltage to obtain a first relationship curve; wherein, the first relationship curve is the relationship curve between the first frequency and the partial discharge quantity of the device under test at each first voltage. For each first relationship curve, calculate the rate of change of each inflection point in the first relationship curve to obtain the candidate inflection point rate of change; The rate of change of each candidate inflection point was screened to obtain the rate of change of the first inflection point; The frequency corresponding to the first inflection point rate of change is determined as the inflection point frequency of the device under test.

4. The method according to claim 1, characterized in that, The sample device is a device of the same model and voltage level as the device under test and meets the preset performance standards.

5. The method according to claim 1, characterized in that, The step of determining the insulation performance status of the device under test based on the first deviation and a preset deviation threshold includes: If the first deviation is less than the preset deviation threshold, the insulation performance of the device under test is good; otherwise, the insulation performance of the device under test is dangerous.

6. A high-frequency, high-voltage insulation diagnostic device, characterized in that, The high-frequency high-voltage insulation diagnostic device is used to perform the method as described in any one of claims 1 to 5, the device comprising: The acquisition module is used to acquire the first partial discharge quantity data of the device under test at multiple first voltages in the operating voltage range and multiple first frequencies in the operating voltage frequency range. The inflection point determination module is used to determine the inflection point frequency of the device under test based on the first partial discharge data of the device under test at each first voltage and first frequency. An insulation performance determination module is used to determine the insulation performance status of the device under test based on the inflection point frequency and the second partial discharge data of the sample device; wherein the second partial discharge data is obtained by measuring the sample device under different voltage and frequency conditions by a measuring device.

7. A computing device, characterized in that, Including memory and processor; The memory stores one or more computer programs, the one or more computer programs including instructions; when the instructions are executed by the processor, the computing device performs the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program for performing the method as described in any one of claims 1 to 5.

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